The ability to easily remove tissue samples (diseased or otherwise) from the interior of a patient's body, along for example the gastrointestinal tract for external ex-situ analysis is a very important part of many medical diagnostic procedures. Known devices for performing this operation include flexible biopsy forceps which are used in conjunction with an endoscope which is inserted by a doctor into the digestive tract of the patient. The biopsy forceps device comprises a long flexible sheath having a cable extending therethrough and includes a pair of pivotally connected jaws attached at one end of the cable and a handle assembly attached at the other end thereof. The handle assembly includes a spool slidably mounted on a shaft connected to the cable in such a way that movement of the spool handle results in opening and closing of the jaws. The endoscope is introduced into the patient's body and then the biopsy forceps device is inserted into the elongate channel of the endoscope and the latter is inserted into the body. The handle assembly of the forceps device is then manipulated by the operator to grip, cut and remove the desired tissue sample.
Known handle assemblies generally include a finger actuated slide or spool slidably mounted on a shaft which is rigidly connected to a thumb ring. Certain types of these handle assemblies include plugs which fit inside the spool and are secured therein by means of set screws and the like. The cable is connected to the plug and the sheath attached to the shaft so that movement of the spool and hence the plug results in movement of the cable with respect to the sheath causing the jaws to open and close. A drawback to this type of arrangement is that the set screws are prone to becoming loose and being lost which can be a great inconvenience and a potential danger during use since the jaws cannot then be properly utilized.
Another type of known handle assembly employs a spool insert which is externally threaded and the spool is internally threaded to receive the plug. The handle assemblies in these devices must be constantly checked to ensure they have not come loose. Another type of spool insert includes a pair of arms connected at a midpoint and the ends of the arms are sized and are deformable so that the insert is received in the spool in such a way so that the end portions of the arms extend beyond the ends of the spool when assembled. Such a device is disclosed in Japanese Laid-Open Utility Model Application No. 58-160010. A drawback to this type of arrangement is that the ends of the arms are prone to being broken thereby rendering the device inoperative. In addition, the arms must be strong enough to withstand stresses related to the opening and closing of the jaws while at the same time being flexible enough to deform during assembly.
Many types of flexible biopsy forceps include a trocar having a sharp point disposed between the jaws. The trocar aids in positioning and fixing the jaws with respect to the tissue to aid in removal of the tissue sample. For example, the trocar is first embedded in the tissue sample with the jaws open thereby anchoring the device so that it does not become dislodged or move around as the jaws are manipulated. In some types of trocar/jaw combinations the trocar is attached to the jaw assembly by means of a pin extending into a hole in part of the trocar and soft soldered to a housing. A drawback to this type of arrangement is that the pin can become loose during ultrasonic cleaning. Some assemblies use a trocar with an integral small tab folded outwards and inserted into a hole in the housing. A drawback to this type of arrangement is that the tab can protrude from the housing thereby presenting a sharp edge which is prone to damage the interior of the endoscope. Also, the tab can break off easily due to its small size resulting in possible loss of the trocar.
Accordingly, it is desirable to provide a flexible biopsy forceps device which provides a handle assembly wherein the finger actuated spool and associated spool insert are securely locked together and not prone to falling apart. In addition, it is desirable to provide a jaw assembly with a trocar affixed to the assembly in such a way that it is not prone to falling apart.